1. Field of the Invention
The present invention relates generally to nondispersive infrared radiation sources and more specifically to a nondispersive infrared radiation source utilized in gas analyzing equipment which is more easily manufactured than the prior art.
2. Discussion of the Prior Art
Gas analyzers are used in the analysis of a medical patient's exhalation gases. The gas analyzer utilizes a radiating light source which is filtered down to a narrow wavelength. The narrow wavelength of light is then passed through a translucent tube containing the medical patient's exhalation gases. The narrow wavelength of light is absorbed by a specific gas. A detector opposite the radiating light source measures the attenuation in frequency of the narrow wavelength of light, after it passes through the specific gas in the translucent tube. The amplitude of the narrow wavelength of light and the attenuated value are calculated by an algorithm to determine the amount of specific gas in the translucent tube.
The prior art in the past has utilized incandescent light bulbs as a radiation source, but more recently, infrared light generated from a thick film resistor has been utilized as a radiation source. Significant prior art in the area of infrared light sources is found in U.S. Pat. No. 5,369,277. The infrared light source in this invention contains many parts which are difficult to make and assemble.
The thick film resistor utilized in the '277 patent is also prone to failure due to the manufacturing process. The thick film resistor is cut from a plate using a laser process that drills tiny holes in the edges of the thick film resistors. The individual thick film resistors are then separated by breaking them off the plate. The resulting breaking leaves micro cracks in the substrate of the thick film resistors which can later lead to premature failures.
Accordingly, there is a clearly felt need in the art for a nondispersive infrared radiation source which is simpler in design, more easily manufactured, and is more reliable than the prior art devices.